The present invention relates to a vehicular exterior trim accessory having a built-in antenna and, more particularly, to an antenna built-in exterior trim accessory formed by a blow molding process of a synthetic resin.
The antenna built-in vehicular exterior trim accessory of this kind is known in the prior art in Japanese Patent Laid-Open Publication No. 104302/1991. What is disclosed in this prior publication is a solid spoiler or sunroof having a built-in antenna, which is manufactured by fitting in a split metallic mold or die for an injection molding a film antenna composed of an electric conductive paint applied in a predetermined pattern on a plastic sheet of ABS or polypropylene, by clamping the mold, and by injecting for example phenol resin material into the mold.
The antenna built-in solid spoiler thus manufactured is made so solid that it takes much resin material, thus raising its cost and making it too heavy for convenient handling. It has, therefore, been desired to develop a hollow exterior trim accessory having a built-in antenna.
A hollow plastic product for the vehicular exterior trim accessory is disclosed in Japanese Patent Laid-Open Publication No. 89824/1986. According to this publication, a fuel tank is formed by blow-molding process wherein a wave-suppressing member is arranged in a plastic parison (a tube of plastic material), the two tip ends of the parison are press-fitted in the mold, and the pressurized air is injected into the parison to be inflated against the counter of the mold. Although the wave-suppressing member is integrated at its two tip ends with the parison, its side edges are spaced from the inner wall face to allow the flow of the internal fluid. As a result, the holding of the wave-suppressing member in the parison is so weak that the member may possibly resonate with the vibration of the vehicle. This problem is serious not for the fuel tank which is filled with the fluid while retaining a sufficient mounting strength with respect to the vehicle's body but serious for the antenna built-in spoiler, i.e., for the structure in which the wave-suppressing member is replaced by the antenna member and the tank is replaced by the spoiler. In short, a device is demanded for mounting the antenna member in the hollow spoiler body.
In addition, in the exterior trim accessory of the prior art, the conductive film antenna is prepared by applying a conductive paint to the plastic sheet so that the adhesion of the conductive film to the plastic sheet is not sufficient. This may deteriorate or deform the conductive film or the plastic sheet by the shearing force resulting from the difference in expansion between the paint and the plastic sheet when heated at the injection molding time or may cause slippage of the conductive film from the plastic sheet.